The recent surge of interest in combinatorial chemistry and automated synthesis has created a renewed interest in polymer-supported reactions. Combinatorial chemistry is a synthetic strategy that leads to large chemical libraries by the systematic and repetitive covalent connection of a set of different xe2x80x9cbuilding blocksxe2x80x9d of varying structures to each other to yield a large xe2x80x9clibraryxe2x80x9d of diverse molecules. It is particularly useful in producing polypeptides or polynucleotides that are currently of interest in the biotechnology area. Polymer-supported reactions or solid phase synthesis is the main methodology used in combinatorial chemistry.
In order to perform combinatorial chemistry in the solid phase, the starting materials are covalently bonded to a polymeric support. Reagents can then be added that react with the starting materials to yield products that are still attached to the support. The main advantage of solid phase synthesis is that the products don""t need to be purified. They can be retained on the solid phase while excess reagents and byproducts are washed away. Then, by successive treatment with different reagents, new molecules are built up on the solid phase. By using a variety of starting materials it is possible to simultaneously build up a library of related compounds by using a single reagent or set of reagents. In this way many new products can be produced in a single reaction vessel.
A wide variety of materials have been developed as polymeric supports and are commercially available. Most of these materials are based on lightly crosslinked polystyrene, a relatively hydrophobic polymer. The crosslinker most commonly used has been divinylbenzene. Crosslinking improves the mechanical properties of the resin but prevents swelling of the resin, which is essential for rapid and thorough reactivity within the polymer system. The hydrophobicity of polystyrene limits its usefulness in many solvents and with many reagents. In order to overcome the problems associated with hydrophobicity, a more hydrophilic material, such as polyethylene glycol (PEG) has been coated onto or grafted to the polystyrene to make it more versatile for solid phase synthesis. This is a very expensive process and still does not completely address the problems associated with the hydrophobic polystyrene matrix. Polystyrene resins have also been crosslinked with more hydrophilic crosslinkers such as bifunctional styrene derivatized PEG chains to crosslink polystyrene in order to improve general resin performance. Improved swelling and mechanical properties have been observed with these resins. However, PEG-based crosslinkers cannot be used with strong bases or organometallic reagents; thus, their usefulness is limited. Additionally, many prior art matrices used for solid phase synthesis have generally low crosslink density and are gel-type polymers. This polymer structure, however, can lead to problems related to reagent diffusion during synthesis. Thus, new and improved resins that can be used for solid phase synthesis are needed.
The purpose of combinatorial chemistry is to generate a large library of related compounds in order to test them for a desired property. For instance, in the drug industry, there is an interest in screening a large number of related compounds for biological activity. Usually these compounds are screened after cleavage from the support. Under these circumstances, the synthesis of combinatorial libraries requires immobilization of the first building block to the support via a linker and cleavage of the compound from the linker after the library synthesis is complete.
The linker is a molecule that can be permanently attached to the support via covalent bonds and also has a reactive group capable of binding, for example, the first building block molecule of the intended synthetic library. After the first building block is attached, further groups are systematically added sequentially until a terminal building block is attached. Finally, the desired library molecules are cleaved from the linker and thus the support. Chloromethylated crosslinked polystyrene is conventionally used to immobilize carboxylic acid building blocks via an unsubstituted benzyl ester. However, these unsubstituted benzyl-type linkers require harsh cleavage conditions, usually liquid HF. There is a need for new linker-functionalized supports that are stable to the reaction conditions used to build the library molecules on the support, but are also able to form an easily cleavable bond with the library molecule under mild conditions to release those compounds at the end of the synthesis.
The present invention provides functionalized supports and methods for use for solid phase synthesis, which are useful in combinatorial chemistry, for example. Functionalized supports described herein can be in the form of a plurality of particles or a membrane, for example. Furthermore, the functionalized support can form a combinatorial library in preferred embodiments.
Generally, preferred functionalized support material (with linker incorporated therein, herein referred to as a xe2x80x9clinker-functionalized supportxe2x80x9d) of the present invention has the formula SSxe2x80x94[NHxe2x80x94(C(R1)(R2))pxe2x80x94C(R3)(R4)(OR7)]m wherein SS represents a support material; R1, R2, R3, and R4 are each independently hydrogen or an organic group (preferably, a (C1-C14)alkyl group, a (C3-C14)cycloalkyl group, or a (C5-C12)aryl group) with the proviso that at least one of R3 and R4 is an aromatic group (preferably, a (C5-C12)aryl group); R7 is hydrogen or an organic group (preferably, including a reactive site, which may optionally be protected by a protecting group); p is at least 1 (preferably, 1 to 20, and more preferably, 1 to 2); and m is 1 to the resin capacity of the support material. Typically and preferably, the NHxe2x80x94(C(R1)(R2))pxe2x80x94C(R3)(R4)(OR7) groups are bound to the support material through a carbonyl group.
Alternatively, preferred functionalized support material (with linker incorporated therein) of the present invention has the formula SSxe2x80x94[C(O)xe2x80x94NHxe2x80x94C(R5)(R6)xe2x80x94(CH2)nxe2x80x94C(O)xe2x80x94NHxe2x80x94(C(R1)(R2))pxe2x80x94C(R3)(R4)(OR7)]m wherein SS represents a support material; R1, R2, R3, and R4 are each independently hydrogen or an organic group (preferably, a (C1-C14)alkyl group, a (C3-C14)cycloalkyl group, or a (C5-C12)aryl group) with the proviso that at least one of R3 and R4 is an aromatic group (preferably, a (C5-C12)aryl group); R5 and R6 are each independently an organic group (preferably, a (C1-C14)alkyl group, a (C3-C14)cycloalkyl group, or a (C5-C12)aryl group); R7 is hydrogen or an organic group (preferably, including a reactive site, which may optionally be protected by a protecting group); n is 0 to 1; p is at least 1 (preferably, 1 to 20, and more preferably, 1 to 2); and m is 1 to the resin capacity of the support material. This material is a preferred example of an azlactone-functionalized support material having a linker attached thereto, wherein C(O)xe2x80x94NHxe2x80x94C(R5)(R6)xe2x80x94(CH2)nxe2x80x94C(O) is derived from an azlactone group.
Yet another preferred functionalized support material (with linker incorporated therein) of the present invention has the formula SSxe2x80x94[C(O)xe2x80x94NHxe2x80x94C(R5)(R6)xe2x80x94(CH2)nxe2x80x94C(O)xe2x80x94NHxe2x80x94(R8)xe2x80x94NHxe2x80x94C(O)xe2x80x94R9]m wherein SS represents a support material; R5, R6, and R9 are each independently an organic group; R8 is an organic connecting group; n is 0 to 1; and m is 1 to the resin capacity of the support material. Preferably, R9 includes a reactive site, which may optionally be protected by a protecting group. Preferably, R5 and R6 are independently a (C1-C14)alkyl group, a (C3-C14)cycloalkyl group, or a (C5-C12)aryl group), and R8 is a (C1-C1000)alkylene group. This material is a preferred example of an amine-modified-azlactone-functionalized support material having a linker attached thereto, wherein NHxe2x80x94(R8)xe2x80x94NH is derived from a diamine.
Use of the functionalized support materials in solid phase synthesis (typically, solid phase organic synthesis) typically requires that the support material includes a linker with a reactive site at which one or more reactions (e.g., synthetic organic reactions) can be conducted. For example, linker-functionalized supports can be used in building polynucleotides and polypeptides, which can then be released from the linker-functionalized supports. They can also be used in developing combinatorial libraries by the systematic and repetitive covalent connection of a set of different xe2x80x9cbuilding blocksxe2x80x9d of varying structures to the reactive site of the linker.
Thus, the support materials described above can be used as the foundation on which such chemical reactions can be conducted if R7 and R9 include a reactive site. This reactive site can include a hydroxyl group (e.g., wherein R7 is hydrogen) or an organic group capable of being derivatized. Alternatively, the reactive site of R7 can be protected with a protecting group, e.g., for a hydroxyl functionality, in cases where that is needed during the step of attaching a linker molecule to the support material.
It should also be noted that the formulations of the support materials described above are used herein to refer to materials that include the final derivatized molecules prior to being removed from the linker-functionalized support. In such cases R7 and R9 may not include a reactive site; rather, they would include, for example, the desired polynucleotide or polypeptide or the desired set of molecules that form the combinatorial library.
The present invention also provides methods that utilize such supports as well as others. In one embodiment, the present invention provides a method of solid phase synthesis that includes providing an azlactone-functionalized support; reacting the azlactone-functionalized support with a linker molecule to form a linker-functionalized support having a linker attached to the azlactone-functionalized support; and conducting one or more reactions on the linker functionalized support. Preferably, this latter step involves reacting the linker-functionalized support with an organic molecule to form a covalent bond between the linker and the organic molecule; and conducting one or more reactions on the covalently bound organic molecule to produce a derivatized organic molecule. The organic molecule is preferably a building block for a combinatorial library. Typically and preferably, the covalent bond formed between the linker and the organic molecule can be cleaved under mild conditions, such as, for example, the use of mild acids or bases, as is well known to those of skill in the art of solid phase synthesis. Thus, typically and preferably, the method involves cleaving the derivatized molecule from the linker-functionalized support at the site of the covalent attachment to the linker.
Preferably, in the method described above, the linker-functionalized support has the following formula SSxe2x80x94[C(O)xe2x80x94NHxe2x80x94C(R5)(R6)xe2x80x94(CH2)nxe2x80x94C(O)xe2x80x94NHxe2x80x94(C(R1)(R2))pxe2x80x94C(R3)(R4)(OR7)]m wherein SS represents a support material; C(O)xe2x80x94NHxe2x80x94C(R5)(R6)xe2x80x94(CH2)nxe2x80x94C(O) is derived from an azlactone group, wherein R5 and R6 are each independently an organic group and n is 0 to 1; NHxe2x80x94(C(R1)(R2))pxe2x80x94C(R3)(R4)(OR7) represents the linker, wherein R1, R2, R3, and R4 are each independently hydrogen or an organic group with the proviso that at least one of R3 and R4 is an aromatic group, R7 is hydrogen, a protecting group (e.g., for an OH functional group), or an organic group capable of being derivatized, and p is at least 1 (preferably, 1 to 20, and more preferably, 1 to 2); and m is 1 to the resin capacity of the support material. In the methods using this material, reactions occur at the xe2x80x94OR7 group.
In another preferred embodiment of the method described above, the linker-functionalized support has the following formula SSxe2x80x94[C(O)xe2x80x94NHxe2x80x94C(R5)(R6)xe2x80x94(CH2)nxe2x80x94C(O)xe2x80x94NHxe2x80x94(R8)xe2x80x94NHxe2x80x94C(O)xe2x80x94R9]m wherein SS represents a support material; C(O)xe2x80x94NHxe2x80x94C(R5)(R6)xe2x80x94(CH2)nxe2x80x94C(O) is derived from an azlactone group, wherein R5 and R6 are each independently an organic group and n is 0 to 1; NHxe2x80x94(R8)xe2x80x94NH is derived from a diamine, wherein R8 is an organic connecting group; C(O)xe2x80x94R9 represents the linker, wherein R9 is an organic group; and m is 1 to the resin capacity of the support material. In the methods using this material, reactions occur at the xe2x80x94R9 group.
Another preferred method of the present invention includes providing an amine-odified-azlactone-functionalized support; reacting the amine-modified-azlactone-functionalized support with a linker molecule to form a linker-functionalized support having a linker attached to the amine-modified-azlactone-functionalized support; and conducting one or more reactions on the linker-functionalized support. referably, conducting one or more reactions on the linker-functionalized support includes reacting it with an organic molecule to form a covalent bond between the linker and the organic molecule; and conducting one or more reactions on the covalently bound organic molecule to produce a derivatized organic molecule. Typically and preferably, the covalent bond formed between the linker and the organic molecule can be cleaved under mild conditions, such as, for example, the use of mild acids or bases, as is well known to those of skill in the art of solid phase synthesis. Thus, typically and preferably, the method involves cleaving the derivatized molecule from the linker-functionalized support at the site of the covalent attachment to the linker.
In yet another preferred embodiment, the present invention provides a method of solid phase synthesis that includes providing a linker-functionalized support having the formula SSxe2x80x94[NHxe2x80x94(C(R1)(R 2))pxe2x80x94C(R3)(R4)(OR7)]m wherein SS represents a support material; NHxe2x80x94(C(R1)(R2))pxe2x80x94C(R3)(R4)(OR7) represents a linker, wherein R1, R2, R3, and R4 are each independently hydrogen or an organic group with the proviso that at least one of R3 and R4 is an aromatic group, R7 is hydrogen, a protecting group, or an organic group capable of being derivatized, and p is at least 1; and m is 1 to the resin capacity of the support material; and conducting one or more reactions on the linker-functionalized support. Preferably, this involves reacting the linker-functionalized support with an organic molecule so as to form a covalent bond between the linker and the organic molecule; and conducting one or more reactions on the covalently bound organic molecule to produce a derivatized organic molecule. Typically and preferably, the covalent bond formed between the linker and the organic molecule can be cleaved under mild conditions, such as those described above. Typically and preferably, the method involves cleaving the derivatized molecule from the linker-functionalized support.
Another preferred embodiment of the methods of the present invention includes providing an azlactone-functionalized support having a linker attached thereto, which has the formula SSxe2x80x94[C(O)xe2x80x94NHxe2x80x94C(R5)(R6)xe2x80x94(CH2)pxe2x80x94C(O)xe2x80x94NHxe2x80x94(C(R1)(R2))pxe2x80x94C(R3)(R4)(OR7) ]m wherein SS represents a support material; C(O)xe2x80x94NHxe2x80x94C(R5)(R6)xe2x80x94(CH2)nxe2x80x94C(O) is derived from an azlactone group, wherein R5 and R6 are each independently an organic group and n is 0 to 1; NHxe2x80x94(C(R1)(R2))pxe2x80x94C(R3)(R4)(OR7) represents the linker, wherein R1, R2, R3, and R4 are each independently hydrogen or an organic group with the proviso that at least one of R3 and R4 is an aromatic group, R7 is hydrogen, a protecting group, or an organic group capable of being derivatized, and p is at least 1; and m is 1 to the resin capacity of the support material; reacting the linker with an organic molecule to form a covalent bond between the linker and the organic molecule; conducting one or more reactions on the covalently bound organic molecule to produce a derivatized organic molecule; and cleaving the derivatized molecule from the azlactone-functionalized support having a linker attached thereto.
Yet another preferred embodiment of the methods of the present invention includes providing a linker-functionalized support having the formula SSxe2x80x94[C(O)xe2x80x94NHxe2x80x94C(R5)(R6)xe2x80x94(CH2)nxe2x80x94C(O)xe2x80x94NHxe2x80x94(R8)xe2x80x94NHC(O)xe2x80x94R9]m wherein SS represents a support material; C(O)xe2x80x94NHxe2x80x94C(R5)(R6)xe2x80x94(CH2)nxe2x80x94C(O) is derived from an azlactone group, wherein R5 and R6 are each independently an organic group and n is 0 to 1; NHxe2x80x94(R8)xe2x80x94NH is derived from a diamine, wherein R8 is an organic connecting group; C(O)xe2x80x94R9 represents the linker, wherein R9 is an organic group; and m is 1 to the resin capacity of the support material; reacting the linker with an organic molecule so as to form a covalent bond between the linker and the organic molecule; conducting one or more reactions on the covalently bound organic molecule to produce a derivatized organic molecule; and cleaving the derivatized molecule from the azlactone-functionalized support having a linker attached thereto.
Whether directed to a method or a support, the present invention includes the following preferred embodiments. he functionalized support can be in the form of a plurality of particles. Each R7 (or R9) can be the same on any one particle, or the plurality of particles can include at least two different R7 (or R9) groups. Alternatively, the functionalized support can be in the form of a membrane. Each R7 (or R9) can be the same on the membrane, or the membrane can include at least two different R7 (or R9) groups.
An xe2x80x9corganic moleculexe2x80x9d (i.e., the starting material) can be a monomer, oligomer, or polymer, although typically it is a monomer. These can be used as the xe2x80x9cbuilding blocksxe2x80x9d in combinatorial chemistry. A xe2x80x9cderivatized organic moleculexe2x80x9d is an organic molecule that is different in some way relative to the starting organic molecule. The organic molecule and derivatized organic molecule can include heteroatoms and substituents as described below with respect to the definition of xe2x80x9corganic group.xe2x80x9d Herein, an organic molecule can also include metals or metalloids, such that it could be classified as an organometallic molecule.
The term xe2x80x9corganic groupxe2x80x9d means a hydrocarbon group (with optional elements substituted for carbon and hydrogen, such as oxygen, nitrogen, sulfur, and silicon) that is classified as an aliphatic group, cyclic group, or combination of aliphatic and cyclic groups (e.g., alkaryl and aralkyl groups). In the context of the present invention, the organic groups are those that do not interfere with chemical reactions that occur at the reactive site of the linker, such as occur in the formation of a derivatized organic molecule. The term xe2x80x9caliphatic groupxe2x80x9d means a saturated or unsaturated linear or branched hydrocarbon group. This term is used to encompass alkyl, alkenyl, and alkynyl groups, for example. The term xe2x80x9calkyl groupxe2x80x9d means a saturated linear or branched hydrocarbon group including, for example, methyl, ethyl, isopropyl, t-butyl, heptyl, dodecyl, octadecyl, amyl, 2-ethylhexyl, and the like. The term xe2x80x9calkenyl groupxe2x80x9d means an unsaturated, linear or branched hydrocarbon group with one or more carbon-carbon double bonds, such as a vinyl group. The term xe2x80x9calkynyl groupxe2x80x9d means an unsaturated, linear or branched hydrocarbon group with one or more carbon-carbon triple bonds. The term xe2x80x9ccyclic groupxe2x80x9d means a closed ring hydrocarbon group that is classified as an alicyclic group, aromatic group, or heterocyclic group. The term xe2x80x9calicyclic groupxe2x80x9d means a cyclic hydrocarbon group having properties resembling those of aliphatic groups. The term xe2x80x9caromatic groupxe2x80x9d or xe2x80x9caryl groupxe2x80x9d means a mono- or polynuclear aromatic hydrocarbon group. The term xe2x80x9cheterocyclic groupxe2x80x9d means a closed ring hydrocarbon in which one or more of the atoms in the ring is an element other than carbon (e.g., nitrogen, oxygen, sulfur, etc.).
As a means of simplifying the discussion and recitation of certain terminology used throughout this application, the terms xe2x80x9cgroupxe2x80x9d and xe2x80x9cmoietyxe2x80x9d are used to differentiate between chemical species that allow for substitution or that may be substituted and those that do not allow or may not be so substituted. Thus, when the term xe2x80x9cgroupxe2x80x9d is used to describe a chemical substituent, the described chemical material includes the unsubstituted group and that group with O, N, Si, or S atoms, for example, in the chain (as in an alkoxy group) as well as carbonyl groups or other conventional substitution. Where the term xe2x80x9cmoietyxe2x80x9d is used to describe a chemical compound or substituent, only an unsubstituted chemical material is intended to be included. For example, the phrase xe2x80x9calkyl groupxe2x80x9d is intended to include not only pure open chain saturated hydrocarbon alkyl substituents, such as methyl, ethyl, propyl, t-butyl, and the like, but also alkyl substituents bearing further substituents known in the art, such as hydroxy, alkoxy, alkylsulfonyl, halogen atoms, cyano, nitro, amino, carboxyl, etc. Thus, xe2x80x9calkyl groupxe2x80x9d includes ether groups, haloalkyls, nitroalkyls, carboxyalkyls, hydroxyalkyls, sulfoalkyls, etc. On the other hand, the phrase xe2x80x9calkyl moietyxe2x80x9d is limited to the inclusion of only pure open chain saturated hydrocarbon alkyl substituents, such as methyl, ethyl, propyl, t-butyl, and the like. A xe2x80x9chydrocarbyl moietyxe2x80x9d refers to an organic moiety containing only carbon and hydrogen atoms (no substituents or heteroatoms).
The term xe2x80x9corganic connecting groupxe2x80x9d means an xe2x80x9corganic groupxe2x80x9d which is situated between and joins at least two chemically reactive groups. In the case of the present invention this term is used preferably to represent the xe2x80x9corganic groupxe2x80x9d which joins two or more amino groups.
The term xe2x80x9clinker moleculexe2x80x9d refers to a molecule that can be permanently attached to a support material via covalent bonds to form a xe2x80x9clinkerxe2x80x9d. The linker molecule (and linker) includes a reactive group capable of binding an organic molecule, which then can be derivitized and cleaved from the support material. Herein, linker molecule refers to the species prior to being attached to the support material and linker refers to the species after it has been attached to the support material.
The term xe2x80x9cmild conditionsxe2x80x9d as it applies to cleavage of the covalent bond formed between the linker and the organic molecule refers to conditions that do not degrade, or otherwise affect, the derivatized organic molecule, but just removes it from the functionalized support. In general, these are conditions well known in the art of solid phase synthesis.
The term xe2x80x9cresin capacityxe2x80x9d or xe2x80x9cfunctional group densityxe2x80x9d means a measure of the amount of functionality of the support material (typically, in the form of a resin), typically described in units such as moles/gram or equivalents/gram of resin.
The present invention provides functionalized supports and methods for use for solid phase synthesis (typically, solid phase organic synthesis), for example. These functionalized supports can be used for synthesizing small molecules as well as large molecules (e.g., biomolecules). Significantly, the functionalized support can be used in solid phase synthesis in which, for example, organic molecules (e.g., monomers) are consecutively added to a chain or polymer, as occurs in the formation of polypeptides, polynucleotides, etc., including peptidomimetics. The functionalized support can also be used to form a combinatorial library if desired, which is of significant interest in a variety of fields, particularly the pharmaceutical industry.
Support Material
Functionalized supports include a support material (often referred to as a base support or base polymer or base resin) and one or more functional groups, preferably, azlactone functional groups. The support material can be a pre-existing material to which functional groups, preferably, azlactone functional groups, are attached (e.g., through the use of high energy radiation and free radical reactions), or the support material and functionalization thereof can occur generally simultaneously (e.g., through the use of free radical polymerization).
The support material can be a polymeric material that can be used in conventional solid phase synthesis. It is chosen such that it is generally insoluble in the solvents or other components used in synthetic reactions that occur during the course of solid phase synthesis.
The support material can be organic or inorganic. It can be in the form of solids, gels, glasses, etc. It can be in the form of a plurality of particles (e.g., beads, pellets, or microspheres), fibers, a membrane (e.g., sheet or film), a disc, a ring, a tube, or a rod, for example. Preferably, it is in the form of a plurality of particles or a membrane. It can be swellable or nonswellable. It can be porous or nonporous. It can be pre-existing or made in situ (such that functionalization occurs during formation of the support material). Preferably, it is made in situ, as occurs in the formation of vinyl azlactone/methylenebisacrylamide copolymer beads.
Examples of useable pre-existing support materials are described in G. B. Fields et al., Int. J. Peptide Protein Res., 35, 161 (1990) and G. B. Fields et al., in Synthetic Peptides: A User""s Guide, G. A. Grant, Ed., pages 77-183, W. H. Freeman and Co., New York, N.Y. (1992). Preferably, the support material is in the form of an organic polymeric material, such as polystyrenes, polyalkylenes, nylons, polysulfones, polyacrylates, polycarbonates, polyesters, polyimides, polyurethanes, etc. For pre-existing support materials, a preferred support material is polystyrene. Included in the term xe2x80x9cpolystyrenexe2x80x9d are polymers that have been substituted to some extent with substituents that are not capable of reaction under the conditions generally used for solid phase synthesis of biomolecules, e.g., substituents such as alkyl and alkoxy groups. In order to increase the stability and insolubility in organic solvents, polystyrene resins are typically crosslinked with, for example, divinyl benzene or butadiene.
Functionalized Supports
Preferably, the support material includes functional groups to which linker molecules can be attached for building large or small organic compounds. Suitable functional groups include electrophilic groups such as epoxide or oxirane groups, N-hydroxysuccinimide ester groups, sulfonyl ester groups, iodoacetyl groups, aldehyde groups, imidazolylcarbamate groups, chlorotriazine groups, or other groups capable of reacting to form covalent bonds with linker molecules, particularly those linker molecules containing amino groups.
In one preferred embodiment, the functional groups are azlactone groups. Typically, azlactone groups are of the formula: 
Azlactone-functionalized supports have been described in U.S. Pat. No. 5,403,902 (Heilmann et al.), for example. They are described as being useful reactive supports for the attachment of functional materials to provide adduct beads. The adduct beads are useful as complexing agents, catalysts, polymeric reagents, chromatographic supports, and as enzyme- or other biomacromolecule-bearing supports. Azlactone beads have high binding capacity with functional materials even when the beads are highly crosslinked and swell very modestly, e.g., threefold or less, in water.
It has now been found that azlactone-functionalized supports, such as these, can be reacted with a linker molecule to form a linker which can be further reacted with a building block molecule (i.e., organic molecules typically used in combinatorial chemistry to build larger molecules such as polypeptides and polynucleotides) through a covalent bond. With certain linkers the covalent bond is cleavable under mild conditions. The building block molecule can then be subjected to numerous chemical reactions using, for example, a combinatorial synthetic scheme to produce a library of compounds attached to the support via the linker. When the covalent bond between the linker and the covalently bound building block molecule is cleaved under mild conditions, the library of organic compounds is released, regenerating the active support (i.e., the functionalized support with linkers attached thereto).
Particularly preferred azlactone-functionalized supports include vinyl azlactone copolymers, such as those described in U.S. Pat. No. 5,403,902 (Heilman et al.). Most preferred azlactone-functionalized supports are vinyl azlactone/methylenebisacrylamide copolymers, such as those commercially available under the trade designation EMPHAZE AB 1 from Minnesota Mining and Manufacturing Company (St. Paul, Minn.) or ULTRALINK Biosupport Medium from Pierce Scientific (Rockford, Ill.). These copolymers are extremely stable to strongly acidic and basic conditions, and thus are ideal base supports for solid phase synthesis.
Typically and preferably, linker molecules can be added to such functionalized supports to create reactive sites for solid phase synthesis. The term xe2x80x9clinker moleculexe2x80x9d refers to a molecule that can be permanently attached to a support material via covalent bonds to form a xe2x80x9clinkerxe2x80x9d. The linker molecule (and linker) includes a reactive group capable of binding an organic molecule, which then can be derivitized and cleaved from the support material, if desired.
The linker is preferably chemically stable to the reaction conditions necessary to derivatize the organic molecule (e.g., and build a combinatorial library). It also preferably is chosen to allow the synthesized molecules to be easily cleaved from the support. The linker may include a protecting group (e.g., a hydroxyl protecting group) at the reactive site, if desired, which can be removed prior to conducting the desired chemical reactions for building larger molecules, for example.
Preferred linker molecules include, but are not limited to, aminoalcohols having the structure H2Nxe2x80x94(C(R1)(R2))pxe2x80x94C(R3)(R4)xe2x80x94OH, such as 2-amino-1-phenylethanol, 2-amino-1-(4-methoxyphenyl)ethanol, 2-amino-1-methyl-1-phenylethanol, 2-amino-1,1-diphenylethanol, 3-amino-1-phenylpropanol, 2-amino-1-phenylpropanol, and the like. Such molecules are readily prepared by cyanosilylation/reduction of aldehydes and ketones as described in Evans et al., J. Org. Chem., 39, 914 (1974) and in U.S. Pat. No. 4,918,231 (Krepski et al.). These linker molecules provide benzylic alcohol functionality similar to the familiar Wang and Rink linkers (described, for example, in Wang, J. Amer. Chem. Soc., 95, 1328 (1973) and Rink, Tetrahedron Letters, 28, 3787 (1987)) commonly used in solid phase synthesis, but in addition contain amine functionality useful for providing stable amide bonds to the support material.
Optically active amino alcohols are other examples of linker molecules. They offer the possibility of conducting asymmetric synthetic transformations on the attached organic molecule. Specific, well-known examples include erythro-alpha-(1-aminoethyl)benzyl alcohol (also known as (1S,2R)-(+)-norephedrine), (R)-(xe2x88x92)-norepinephrine, (S)-(+)-norepinephrine, L-erythro-2-(methylamino)-1-phenylpropanol (aka 1-ephedrine), D-threo-2-(methylamino)-1-phenylpropanol (also known as d-pseudoephedrine), and d-2-amino-1-phenylethanol.
In addition to the preferred linker molecules described above, many of the traditional linker molecules commonly utilized for solid phase synthesis can also be used with azlactone-functionalized supports provided that these supports are suitably derivatized to allow attachment of the traditional linker molecules. Preferably, this derivatization process involves reaction of the azlactone group with an excess of a polyamine, to produce an amine-modified-azlactone-functionalized support. Examples of polyamines include primary polyamines, such as ethylenediamine, 1,3-propanediamine, 1,3-diamino-2-hydroxypropane, 1,6-hexanediamine, tris-(2-aminoethyl)amine, and the like; and polyetherpolyamines, such as 4,7,10-trioxa-1,13-tridecanediamine, 3,6-dioxa-1,8-diaminooctane, amine-terminated polyethyleneglycol and polypropyleneglycol homopolymers and copolymers; and the like. Preferably, the polyamines are diamines, such as ethylenediamine, 1,3-propanediamine, 1,3-diamino-2-hydroxypropane, or 1,6-hexanediamine. In a second step, carboxyl functional linker molecules can be reacted with the amine to form an amide bond to the support. Examples of suitable linker molecules include, but are not limited to, 4-hydroxymethylbenzoic acid, 4-hydroxymethylphenoxyacetic acid, 4-hydroxymethyl-3-methoxyphenoxybutyric acid, 4-hydroxymethylphenylacetic acid, 4-bromoacetylphenoxyacetic acid, 4-(diphenylhydroxymethyl)benzoic acid, 4-hydroxymethyl-2-methoxy-5-nitrophenoxybutyric acid, phenoxyacetic acid and phenoxybutyric acid analogs of Rink acid and Rink amide linker molecules and Sieber amide linker molecules (described, for example, in Rink, Tetrahedron Letters, 28, 3787 (1987) and Sieber, Tetrahedron Letters, 28, 2107 (1987)), 4-sulfamylbenzoic acid, 4-sulfamylbutyric acid, 4-formylphenoxyacetic acid, 4-(4-formyl-3-methoxyphenoxy)butyric acid, 4-formyl-3,5-dimethoxyphenoxyacetic acid, 3-formylindol-1-ylacetic acid, and the like. This synthetic scheme preferably results in a resin of the general structure SSxe2x80x94[C(O)xe2x80x94NHxe2x80x94C(R5)(R6)xe2x80x94(CH2)nxe2x80x94C(O)xe2x80x94NH-(organic group from amine)-NHxe2x80x94C(O)-linker]m.
The linker molecules can be attached to the support material using conventional attachment chemistry, such as carbodiimide chemistry, mixed anhydride chemistry, and the like. Such techniques are well known to one of skill in the art.
Once attached to the functionalized support, the linker provides one or more reactive sites for subsequent reaction, such as those that occur in solid phase synthesis (typically, organic synthesis). Such functionalized supports having a linker attached thereto are referred to herein as linker-functionalized supports. The reactive site can include a hydroxyl group or an organic group capable of being derivatized. Alternatively, the reactive site can be protected by a protecting group, e.g., for a hydroxyl functionality, in cases where that is needed during the step of attaching a linker molecule to the support material. Examples of such protecting groups include t-butyldimethylsilyl, triphenylmethyl, and others well known in the art (see, for example, Harrison and Harrison, Compendium of Organic Synthetic Methods, pages 124-131, John Wiley and Sons, New York, 1971). Such protecting groups are removed during the process of conducting reactions on the linker.
It should also be noted that the formulations of the support materials described herein are used herein to refer to materials that include the final derivatized molecules prior to being removed from the linker-functionalized support. In such cases the linkers (which include, for example R7 and R9 in the formulations herein) may not include a reactive site; rather, they would include, for example, the desired polynucleotide or polypeptide or the desired set of molecules that form the combinatorial library. As a result they can be quite large.
Preferably, a linker-functionalized support has the following formula SSxe2x80x94[C(O)xe2x80x94NHxe2x80x94C(R5)(R6)xe2x80x94(CH2)nxe2x80x94C(O)xe2x80x94NHxe2x80x94(C(R1)(R2))pxe2x80x94C(R3)(R4)(OR7)]m wherein SS represents a support material; R1, R2, R3, and R4 are each independently hydrogen or an organic group (preferably, having up to about 20 carbon atoms) with the proviso that at least one of R3 and R4 is an aromatic group; R7 is hydrogen or an organic group; R5 and R6 are each independently an organic group (preferably, having up to about 20 carbon atoms); n is 0 to 1; p is at least 1 (preferably, 1 to 20, and more preferably, 1 to 2); and m is 1 to the resin capacity of the support material. Preferably, C(O)xe2x80x94NHxe2x80x94C(R5)(R6)xe2x80x94(CH2)nxe2x80x94C(O) is derived from an azlactone group and NHxe2x80x94(C(R1)(R2))pxe2x80x94C(R3)(R4)(OR7) represents the linker. Preferably, when OR7 is the attachment site for an organic molecule, R7 is hydrogen or an organic group capable of being derivatized, as in combinatorial chemistry, for example. Alternatively, the organic group could be a protecting group for, e.g., a hydroxyl functionality, in cases where that is needed during the step of attaching the linker to the support. Prior to any reactions being conducted on the linker-functionalized support, the protecting group is removed. For certain embodiments, R7 can include the final desired product. As a result it can be quite large, including polynucleotides and polypeptides, for example.
Another preferred linker-functionalized support has the following formula SSxe2x80x94[C(O)NHxe2x80x94C(R5)(R6)xe2x80x94(CH2)nxe2x80x94C(O)xe2x80x94NHxe2x80x94(R8)xe2x80x94NHxe2x80x94C(O)xe2x80x94R9]m wherein SS represents a support material; R5 and R6 are each independently an organic group (preferably, having up to about 20 carbon atoms); R9 is an organic group; R8 is an organic connecting group (preferably, having up to about 1000 carbon atoms); n is 0 to 1; and m is 1 to the resin capacity of the support material. R8 can be any linear or branched organic group and is preferably derived from diamines. Examples of such diamines include primary diamines, such as ethylenediamine, 1,3-propanediamine, 1,3-diamino-2-hydroxypropane and 1,6-hexanediamine, and the like; and polyetherdiamines, such as 3,6-dioxa-1,8-diaminooctane, amine-terminated polyethyleneglycol and polypropyleneglycol homopolymers and copolymers; and the like. Preferably, C(O)xe2x80x94NHxe2x80x94C(R5)(R6)xe2x80x94(CH2)nxe2x80x94C(O) is derived from an azlactone group, NHxe2x80x94(R8)xe2x80x94NH is derived from a diamine, and C(O)xe2x80x94R9 represents the linker. Preferably, NHxe2x80x94(R8)xe2x80x94NH is derived from ethylenediamine, 1,3-propanediamine, 1,3-diamino-2-hydroxypropane, or 1,6-hexanediamine.
Preferably, when C(O)xe2x80x94R9 is the linker, it includes an attachment site for an organic molecule. Such attachment sites can be the same as those described above for R7 (e.g., hydroxyl group, an organic group capable of being derivatized, or a protecting group). Preferably, C(O)xe2x80x94R9 is derived from 4-hydroxymethylbenzoic acid, 4-hydroxymethylphenoxyacetic acid, 4-hydroxymethyl-3-methoxyphenoxybutyric acid, 4-hydroxymethylphenylacetic acid, 4-bromoacetylphenoxyacetic acid, 4-(diphenylhydroxymethyl)benzoic acid, 4-hydroxymethyl-2-methoxy-5-nitrophenoxybutyric acid, phenoxyacetic acid and phenoxybutyric acid analogs of Rink acid and Rink amide linker molecules and Sieber amide linker molecules, 4-sulfamylbenzoic acid, 4-sulfamylbutyric acid, 4-formylphenoxyacetic acid, 4xe2x80x94(4-formyl-3-methoxyphenoxy)butyric acid, 4-formyl-3,5-dimethoxyphenoxyacetic acid, or 3-formylindol-1-ylacetic acid. For certain embodiments, R9 can include the final desired product. As a result it can be quite large, including polynucleotides and polypeptides, for example.
Alternatively, a linker-functionalized support does not necessarily have to be derived from azlactone functionality, but can have the following formula SSxe2x80x94[NHxe2x80x94(C(R1)(R2))pxe2x80x94C(R3)(R4)(OR7)]m wherein SS represents a support material; R1, R2, R3, and R4 are each independently hydrogen or an organic group with the proviso that at least one of R3 and R4 is an aromatic group; R7 is hydrogen or an organic group; p is at least 1 (preferably, 1 to 20, and more preferably, 1 to 2); and m is 1 to the resin capacity of the support material. Preferably, NHxe2x80x94(C(R1)(R2))pxe2x80x94C(R3)(R4)(OR7) represents a linker. It is typically attached to the support material through a carbonyl group, thereby forming an amide linkage. Preferably, when OR7 is the attachment site for an organic molecule, R7 is hydrogen, an organic group capable of being derivatized, or a protecting group, which would be removed prior to any reactions being conducted on the linker-functionalized support. More preferably, R7 is hydrogen. For certain embodiments, R7 can include the final desired product. As a result it can be quite large, including polynucleotides and polypeptides, for example.
When the functionalized supports include organic groups at the R1, R2, R3, R4, R5, R6 and R8 positions, these can be of any size or functionality that do not interfere with the solid phase synthesis reactions. Preferably, R1, R 2, R3, R4, R5, and R6 are each independently alkyl groups (preferably, containing 1 to 14 carbon atoms, and more preferably (C1-C14)alkyl moieties) or cycloalkyl groups (preferably, containing 3 to 14 carbon atoms, and more preferably (C3-C14)cycloalkyl moieties), aryl groups (preferably, containing 5 to 12 ring atoms, and more preferably (C5-C12)aryl moieties). Preferably, at least one of R3 and R4 is an aryl group (preferably, containing 5 to 12 ring atoms). Any two of the groups R1 and R2 or R5 and R6 taken together with the carbon to which they are joined can form a carbocyclic ring, preferably containing 4 to 12 ring atoms. Preferably, R8 is an alkylene group (more preferably, an alkylene moiety) having up to about 1000 carbon atoms.
Functionalized supports (including linker-functionalized supports) of the present invention can have the same or mixtures of functional groups and/or linkers. For example, support materials as described herein can include at least two different R7 (or R9) groups. If particles are used, this can result from blending two different samples of particles, each with a different R7 (or R9) group. Alternatively, a membrane can include at least two different R7 (or R9) groups.
Base functionalized supports can be prepared by methods well known in the art, and many are available commercially (e.g., from various companies such as Novabiochem, BioRad, Pierce, Amersham-Pharmacia, Rapp Polymere, Polymer Laboratories, Sigma-Aldrich, Millipore, EM Separations, etc.). Methods for the preparation of azlactone-functionalized supports are described, for example, in U.S. Pat. No. 5,403,902 (Heilmann et al.). This patent describes the preparation of particulate supports by suspension or dispersion polymerization processes. Other methods for preparing useful azlactone-functionalized supports are described in U.S. Pat. No. 5,262,484 (Coleman et al.), which describes graft copolymers and articles prepared therefrom, U.S. Pat. No. 5,292,514 (Capecchi et al.), which describes functionalized substrates, U.S. Pat. No. 5,451,453 (Gagnon et al.), which describes porous supports, U.S. Pat. No. 5,486,358 (Coleman et al.), which describes polymer blends and articles prepared therefrom, U.S. Pat. No. 5,510,421 (Dennison et al.), which describes membrane supports, and U.S. Pat. No. 5,993,935 (Rasmussen et al.), which describes bead/porous matrix composites.
Use of the Functionalized Supports
The functionalized supports are preferably used to covalently attach a linker molecule and to provide a starting point for solid phase synthesis of a compound, which may or may not be polymeric. For example, in creating a combinatorial library, the functional groups with linker and organic molecule attached thereto can be divided into groups and then chemically modified by introduction of substituents to form a series of analogs. Alternatively, conventional formation of a polymer (e.g., homopolymer, copolymer, terpolymer, etc.) by stepwise addition of monomers can occur.
Conventional solid phase synthetic techniques can be used. Such synthetic techniques can include the use of protecting groups. These can be deprotected using appropriate cleavage reagents well known to those of skill in the art.
After synthesis is complete, cleavage conditions are used to remove the modified organic molecule (i.e., organic compound), preferably by cleaving the covalent bond between the linker and the organic molecule. Preferably, the cleavage conditions are mild, whether they be acidic or basic. Typically, mild conditions involve the use of acids (particularly acids having an H0 of xe2x88x925 or higher, as defined by J. P. Tam et al. in The Peptides, Vol. 9, S. Udenfreind and J. Eienhofer, Eds., pages 185-248, Academic Press, New York, N.Y. (1987)), such as hydrochloric, acetic, sulfuric, and trifluoroacetic acid. Preferably, trifluoroacetic acid is used. Basic cleavage conditions may also be used through the use of, for example, sodium hydroxide or ammonia solutions. Other useful common methods of cleavage are reviewed in numerous literature articles, for example, in xe2x80x9cThe Combinatorial Chemistry Catalogxe2x80x9d published annually by Calbiochem-Novabiochem, San Diego, Calif.
The method of using the functionalized supports described herein is particularly useful in preparing a combinatorial library. Specifically, in making such a library, a plurality of reaction vessels are provided, each containing a functionalized support with a linker attached thereto. A different monomer, each capable of reacting with the linker on the functionalized support, is provided in each vessel. Additional monomers are coupled to the growing oligomer chain, with the identity and order of monomers documented to enable synthesis of a plurality of support-bound, chemically distinct oligomers. This last step may involve a xe2x80x9csplit/mixxe2x80x9d approach, wherein after every monomer addition, the contents of the reaction vessels are alternatively divided and mixed in a way that provides for a completely diverse set of ligands. The distinct oligomers in the combinatorial library so provided are then screened for activity, generally by screening individual sublibraries containing mixtures of distinct oligomers, identifying active sublibraries, and then determining the oligomeric compounds of interest by generating different sublibraries and cross-correlating the results obtained.